Power actuator



Oct. 6, 1931. C, s, BRAGG Ej- AL 1,826,450

POWER ACTUATOR Original Filed June 20, 1928 2 Sheetsheet l l T, mmm

. Nj-555,5 ATTORNEY Oct. 6,- 1931. c. s. BRAGG ET Al. 1,825,450

' PowER AcTUAToR b Original Filed June 20, 1928 2 Sheets-Sheet 2 l ATTQRNEY Patented Oct. 6, 1931* NITE); STATES .PATENT OFFICE lcALEJs s. Bruce ANnjvIcron w.- xLrEsnA'rn, on LoNG ISLAND crrY, Nnw Yonx, As-

sreNoRsro BMGG-,xLIEs'Ra'rHconn-ORATION, or LONG ISLAND CITY, Nnw- Yonx,

A CORPORATION NEW YORK POWER crearon Application led,o .'lune20,` 192,8, Serial Our invention consists in the novel features hereinafter described, reference beinghad to the accompanying drawings which illustrate several' embodiments of the same, selected by us f or purposes of illustration, and the said Invention is fully disclosed in thefollowing description and claims. A

Our present invention relates td vacuum L brake systems for automotive vehicles, and

consists in the provision of an improved controllingvalve mechanism for a suction actuated power actuator interposed between the power actuatorand the suction and higher fluid pressure sources, 'and comprising among its members a valve actuating part operatively connected with two diaphragm valves, the construction of said valve mechanism being such that each of the diaphragm valves is always maintained in seated position bythe vdilferential of fluid pressures .on its o po site faceswhenever such differential of uid pressures exists, which is obviously the onl time when a valve is required to be firmly seated, thereby insuring against leakage, and.

producing' a more reliable valve, and effecting a saving in manufacturing costs, by the eliminationl of springs. In other words,

when either diaphragm is seated and a differential of .uid' pressures exists upon its oppositefaces, said differential of iuid ressures acts uponthevalve to hold it more firm-- ly seated andprevent leakage. I l

In the preferred form of our invention, when theiparts are in the'normal or released position, relatively smaller areas of the opposite facesof one diaphragm valve are sub- .jected-to the maximum diferential of Huid pressures in adirection acting to resist the movement of the diaphragm valve b theoperator and to hold said diaphragm 1n seated position, while relatively larger areas of the opposite faces of theother diaphragm are subjected to equal fluid pressures,the differential of fluid pressures on the smaller faces of said rstmen'tioned diaphragm providing the initial resistance to the operation of the valve mechanism by the operator. When, however, the valve'mechanism is'operated to effect a power stroke of theactuator to apply the 'brakesfluid pressure on the relatively No. 286,803. Renewea'march e, 1931.

'smaller opposite faces of the-first mentioned diaphragm are equalized as the'relatively larger areas of the opposite faces of the other diaphragm are exposed to the gradually in creasing differential of fluid pressures actmg .in'opposition to the movement of the operator to maintain the second -mentioned l diaphragm unseated and-corresponding substantially with the increase in the differential of fluid pressures on the movable pressure operatedpart of the power actuator, thus ,buildingup a lresist-ance which will be felt yto the actuator in linkage between the operator operated part and the brake mechanism of the vehicle, preferably the brake mechay nism to which the poweractuator is 'opera-l tively connected, provision being made to limit the relative movement between the valve actuating part and the casing of the valve mechanism, to enable the operator to apply his ,physical force to the brake mechanism in addition to t-he power exerted thereon by the actuator 'or for the purpose of applying 'the connected brake mechanism by physical for-ce alone in case of failure of power.

Our invention also includes certain novel features of construction and combination of parts hereinafter fully described and particularly pointed out in the claims.'

Referring to the accompanying/drawings,

lwhich illustrate two embodiments of our invention, selected byus for purposes of illustration. t

Fig. 1 is a dia rammatic representation showing a vacuum rake system for an automotive vehicle, embodying our present inven- `tion.

Fig. '2 is an enlarged sectional View 'ofthe Controlling valve mechanism illustratedv in Fig. 1, the parts being shown inthe released or olf position.- v,

Fig. 3 is a 'similar view showing the parts in the positions which they occupy when moved to'efect the power stroke of the actu-il ator. l" f Fig. 4' is a view similar toFig. 2,'-showing a slightmodifcation of our invention. 2' 5 Fig. 5 is a partial sectional view, similar thereto.-

Fig. 7 `isa view similarto Fig. 1 showing a slight modification. A f

Referring to Fig. 1, W, W,/repr esent the frontV or steering wheels of an automotive ve- '15 hicle, provided with brake mechanisms, indicated as awhole atB, B, and W', W', are Athe non-steering or traction wheels, which are shown in thisinstance provided with brake mechanisms, indicatedl as a Ywhole at B", 1B',A which brakel mechanisms may be of any usual or desiredconstruction.V In the present instance each of said brake mechanisms is shown as comprising a brake drum,

70, a brake band, 71, a brake operating lever,

'25 72, provided with la'retracting spring, 73,

'the levers, 72 o f the front wheel brake mechanisms being operatively, connected by links, 74, with arms, 75,-on a rock shaft, 76,f and the lever s,`72,"of the rear wheel brake mechl anisms being. connected by links, 74', with arms, 75', on a rock-shaft, d', P'represents the power actuator, comprising in t is instance a cylinder, 1, closed at bothI ends, by

heads, 2,. 2, and provided with a piston, 3,

but movable with respect tov tli'e vehicle, the

cylinder being connected with, and' conveniently supported by, arms, 77 on the rock shaft, 76', and thepiston, 3, being connected. by a link, 78, with an arm, 77, on the rock 40 shaft, 7 6, so that therelative movement of the piston and cylinder will .apply and release both sets. of brake mechanisms simultane- 'ously.v l i the ower actuator is indicated at V, Yas a mechanism is constructed, for example, as

illustrated in Figs. 2 and 3. l f v `For' convenience of manufacture and assembly, the casing of the valve mechanism is preferably formed in, three parts, to wit, a` e central member, 6,A and a f, and 6,'respectively, constructedandarf. ranged as hereinafter described, and united' in any suitable manner, 'as foifexamplafby. v The centrali-gt;,a'siijig niem-A ber,"6, isf rovided with yan interior central chamber, having. anputletaperture, 7*, which in this instance isjconnected by 'a ilexible tubing, 14s, with thegcylinder,1, ofthe 00 actuator, in'rear .of .thevpiston therein. I-n.- the'form 'of the invention shown' in Figs. 2

. and A3,.' the'central-casing member is also pro- .vided atone side' ofthe chamber, 7, with an y. inwardly extending .annular flange, 7 b, hav

6l gan ,annular groove, 7c, on-its outerface,M

The controlling valve mechanism for air'` of end plates',

and forming an'annular seat,7w, adjacent to I rately on the adjacent face of the central casing member, 6, and is provided with a clamp-4 ing face, 6d, between which and the clamping face, 7d, the marginal portions' ofa -iieXible diaphragm valve, indicated at 8, are securely clamped `so as to make an air tight. joint therewith', land between the sections of the .valve casing.' The end plate, 6a, is provided interiorly withan annular diaphragm -the inner edgeof said iiange.` The-central' casingvmember is also provided at the oppo-A site end thereof with an annular clamping face, indicated-at 7 d. The end plate 6a, of lthe casing, shown as therearend plate in Figs. 1, 2 and 3, is constructed to t accu-v engaging seat, indicated at 11, which, when 'the' diaphragm is 'seated thereon, divides the space within said end plate into a central chamber, 13, and an annular chamber, l2, one of which is connected tothe source of suction, and the vother ofI which is connected to the actuator cylinder forward of the piston.

In this instancethe annular chamber, 12,

which we term the suctionchamber of'the valve cas1ng,is connected by a pipe, 32, with the suction passage of the internal combustion engine for propelling the vehicle, or vei hicles- (as in the case of a tractor or trailer).

.In Fig. 1, the engine is indicated at 60, and

is shown provided with a suction passage, includinga vertical portion, 62, and the usual intake manifold, 61, said suction passage leading from the carburetor, indicated at 64, tothe engine cylinder, and the vertical portion, 62, thereof, being provided with the usual throttle valve indicated at 63. The suction pipe, 32, before referred to, is connected tothe suction passage between the throttle valve and the engine cylinders, and preferably is connected to the intake 'manifold, 61, as shown, andi is provided with a check valve, 65, opening in the direction of the small arrow lin Fig. 1, that isto say,

5 who e, and the preferred form of our valve vtoward the intake manifold. The central chamber,l 13, of`the end plate, 6a, is connected` by. means of a flexible pipe, 32a, with the acn tuator cylinder, 1, forward of the piston therein; The annular seat, 11, is provided with anqaperture therein, indicated at ll,

which places the suction chamber, 12, at yall f times in e communication with the central chamber,.13, so` thattheforward end of the "-.eylinder is at all times maintained in direct Pepinmunication with the intake manifold. *Within the central chamber, 13,', is locatedl acdisc valve, 10 provided with en -annular diaphragm'engagingseat, 10a, and forming achamber, indicated at 10b, between the diaphragm ,8`, 'and the disc valve, 'which com-I municates 'at all times with the chamber, .-7,

inthe central "casing lmember,"6, by means of apertureS,-. 19z`,in thediaphragm, 8'. The disc,

.' 10, and diaphragm; 18,. have their central po'rtions sealingly securedto a valve actuating s in vipart, indicated` at 20, eXtending-throuvha central aperturein the forward end 'Ilate, 6b, as hereinafter described, and we prefer to provide the.discfvalve,'-10, with a, guiding portion, 10c, 'engaging a; guiding recess, 13a,

in, the end plate, 6a, although. this is not essential. The end plate,'6a,.is also provided l with 'means for connecting 1t, as hereinafter described, in linkage between an operator operated part anda brake mechanism'operated bythe power actuator, being shown provided with a boss, 6e, having an vinternally threaded aperture to receive the threaded end of a link rod, 79.

` The forward end plate, 6b, of vthe valve casing is provided with an annularl clamping shoulder,16f, for clamping the marginal por-l v tions of a diaphragm, 15, between the flange,

(if, and the Hange, 7b, of the Icentral casing member, and forming van air tight connectionbetween the'parts. This diaphragm, 15, is

' normally' seated uponth'e annular seat, 7m,

ofthe flange 7b, and the central portions of the, diaphragm are sealinglysecured to the valve actuating part, 20, in any usual or desired manner, soas to move the diaphragm, 15, toward-or away. from the seat, 7x. The

l diaphragm is provided with an annular portion, 15a, of comparatively small ar'ea between the seat, 7m, and the valve actuating part, which is not supported by the flange,

7 b, in thenormal position of the parts, indicated in Fig. 2," and the end plate, 6?), isl provided with a chamber, indicate-d at 16, on the outer face of the diaphragm, 15, which is at allA times in communication with the atshown an operator operated part, consisting mosphere through an aperture, or apertures, 17. We preferably provide -anair strainer, 18, having inlet apertures, 18a, for preventing the admission of dust to the interior of the valve casing. rlvhe valve actuating part, 20,

extends through a guidingsleeve, 21, located:

centrally of thel endv plate, 6b, andis y pro-V vided with means for attaching it in the linki ,.5 Qage betweenthe operator operated part and a brake mechanism of the vehicle, being in this instance provided with an interiorly threads ed aperture, 22, to receive the threaded end of a link rod, 82.

In the installation shown in Fig. 1, we have of a foot lever, 80, which is provided with the 'usual retracting spring, 81, and in this inoperating the rear'v or non-steering wheelvr stance we have shownthe 8 2, connected with the foot lever, andthe rod, 7 9,. connected with an arm,'77a, on therockshaft, 76', for

brake mechanisms.- Thel spring, 81, need only be suficient to counterbalance the weight of the foot lever.

- v Assumingthat the parts of thel valve mechanism are in the .normalposition indicated in Fig 2, and that the engine is running, and

the throttle valve Aclos'ed',for.I partly closed,.

`rareecation in the intake manifold will eX-4 haust the air from the suction pipe, 32, and from the cylinder forward of the piston,

11a, and the suction chamber 12, and, a's in the normal position of the valve mechanism, the seat, 10a, of the disc valve, 10, is out of engagement with the diaphragm, 8, the cenltral chamber, 7, will be placed in communication with the chamber, 12, through the 'apertures,19 in the diaphragm, and the un seated disc valve, 10, and hence the air will alsobe exhausted from the actuator cylinder in rear of the piston through the pipe, 14. .A partial vacuum is therefore maintained with- 'through the pipe, 32a, chamber, 13, passage,`

in the actuator cylinder on bot-h Vsides of theJ piston, which is therefore, as we .term it,

maintained submerged in vacuum. Thecheck valve,65, in the suction pipe, 32, also insures that the degree of rarecation in the cylinder on both sides of the piston, also within the valve'mechanism, shall be the ma'xi- 'mum degree of rarecation which occurs in the manifold between operations of theactuator to apply the brake mechanism. It will' also be seen that inthe released position "of the valve mechanism illustrated in Fig. 2

pressures are equalized on the opposite faces Y of the diaphragm, 8, as both soides are subjected on its outer face to atmospheric pressure, and the portion of said diaphragm with' in the seat,"7m, is subjected on its inner face to the rarelication in chamber,7, so that the diaphragm, 15, is held seated uponvthe flange, 7 b, and the seat, 7a2, by the differential of fluid pressures upon a small area of the dia-v phragm within the seat, 7m. This differential of fluid-pressure is applied to the valve` actuating stem, 20, in a direction to hold the fjected to the degree of rarefication existing in the cylinder. The diaphragm, 15, is subdiaphragm, 15, seated on the seat, 7m, and to maintainthe disc valve, 10, Aunseated with respectl to the diaphragm, as indicated in Fig. 2. The diaphragm, 15, is provided with oneor more air inlet apertures, indicated at 23, communicating with the ann'ularrecess, 7 c, in the flange, 7 b so that fluid pressures are Vsubstantially equalized on the diaphragm, 15,

fore stated, need only be sufficient to counter' balance the weight of the pedal lever, 80.

To elect an application of the'brakes, the operator will place his foot on the'pedal le'- ver, 80, and press it forward, in the direction of the arrows, Figs. 1, 2v, and 3. Thijs will' seat the discvalve, 10, on the diaphragm, 8,

separating the central chamber, 7 from communication with the chamber, 13, and with the suction passage by way4 of pipe,`32, and the en d of the cylinder connected by way of the S casing members, 6, and 6a,

cumulating in the central cham er, 7,

V phragm, 8, and

pipe, 32a, but leaving the ,forward portion of the cylinder yof the actuator'in communicavtionwith the manifold through pipes, 32a and 32. Thereafter the diaphragm, 15, willv 5fbe unseated from the seat, 7m, thereby placing the central chamber, 7 of the valve casing in communication with the' atmosphere, through the apertures, 23, in vthe diaphragm, 15, and thus admitting atmospheric air to said 10 chamber7, and through the pipe, 14., to the end of the actuator cylinder connected therewith, where pressures will accumulate and eflfect a power stroke of the actuator to apply brake mechanisms for the-steering and non- 15 steering wheels simultaneously. It will also l beseen by reference to Fig. 3, which showsthe parts inl the positions above described, that the disc valve, 10,-.and the portion of the diaphragm between the valve seat, 10a and the actuator, andv will beexertedin a direction 35 to move the valve actuating part, 20, rearor aga-inst the direction. in which .it

wardly i pplication is-moved by the pedal lever for an a vof the brakes, so that a gradually lncreasing yresistance will be felt by the operator corre- 40 spending .proportionately with the amount of pressure exerted on the brake mechanism by the power actuator, lwhich will apprise the op- .erator as to the extent to which the brakes are being applied. I It. will be understood that during the power stroke of vthe actuator, the s fluid pressures on opposite faces of the diaphragm, 15, will be correspondingly reduced. [t willv also be understoodJ that the entire 1- valve mechanism will move forward with the pedal lever during the power-stroke of the actuator, and that as long as the forward movement ofthe pedal lever contmues,and

are sub]ected on casing through the rock shaft, A76', will move the valve casing in the direction of the arrow,

Fig. 3, with respect to the valve actuating part and permit the diaphragm, 15, to seat on the seat, 7m, preventing 'a further admisysion of atmospheric air, without, howerer,

unseating the discA valve, .10, from the diahragm 8, thus vholding the brakes as ap- P Ehed. Further power may be applied to the rakesby the actuator, by a further movement of the pedal lever, 80, until the maximum power of the actuatorhas been exerted upon the brake mechanisms with which it is connected.

We also provide means for limitingthe relative movement between the valve actuating part, 20, and the valve casing. In this instance the valve actuating part is provided with a collar, 24, adapted to engage'the forward end plate, 6b, to limit the relative movement between said part, and it willfbe obvious that the operator,by taking up this lost motion, can apply his physical force directly to vthe brake mechanisms for the rear or nonsteering wheels with which the rod, 79, is

connected, in addition to th'e power exerted thereon by the actuator and lwlthoutgincreasing the braking force. ofthe steering wheel brake mechanisms, or-forthe purpose of operating the brake mechanisms for the nonsteering wheels, by physical force alone in case of failure of power, in which case vthe relative movement of the valve actuating part and valve casing in taking up the lostmotion would place vthe valves in position to vent the cylinder.'

; It will be understood that vthe valve mechanisms shown in Figs. 1,-2 and 3 can be em-l` ployed to control one or any number of powerv actuators which may be located upon the same or upon different vehicles, andconnectedby. suitable/ piping with the valve mechanism or with the actuator, P. For example, in Fig. 1, we have shown theI actuator cylinder, 1, provided with pipes, '35 and 36,

faces of the piston, for connecting the valve mechanism, V, inthis instance through the cylinder,I '1, withthe corresponding portions of the cylinder, or cylinders, of another actuator, or other actuators, in which case all of the actuators would be controlled simultanecommunicating with the cylinder on opposite fthe operator overcomes the increasing resistnously by the valvemechanism, V. VThe pipes, 35 and 36, are shown provided with cuto ance to its forward movement, atmospheric valves, 37, and 38, respectively, so that'they 55 air will be delivered to the actuator'cylinder onl one side of the piston and the-power. stroke will continuevwithout, however'. admitting Vanyappreciable quantity of'air from thev- "actuator cylinder forward'of the piston to the intake manifold, thus obviating'any danger of stalling the engine, if idling, during the application of the brake mechanism." -As soonas the forward movement ofthe pedalJ lever ceases-,a slight continued movement of G51-,he cylinder, isconnected to the valveA may be closed whenno other actuators are to be connected. v Y v -To' release thebrakemechanisms after they have been applied Fby the power a"ctul ator, the operator will release the-pressure of his foot on the pedalllever, or remove his foot altogether when thediil'erential of fluid preswill force the valve actuating part rearward- 1y so as to unseat-it from the diaphragm, 8,

sures on oppositel faces ofthe disc valve, 10,-

oringthe parts to the position shown in Fig. 2J The'diaphragm, 15, has already seat-v ed itselfon the seat, 7 and shut off the cen tralchamber, 7 ,p from communication with theatmosphere, and as soon as the disc valve, .10, is unseated, the chamber, 7, will be placed in communication with-the chamber, 13,vvith the suction passage ofthe engine through the pipe, 32, and with the other end of the cylinder through the pipe, 32a, and the air previvouslyadmitted to the actuator cylinder will be withdrawn. Fluidpressures on opposite v faces of the piston and cylinder and upon opposite faces ofthe diaphragm, 8, andv disc valve, 10, will be equalized by the withdrawal y of air from the cylinder on one 4side of the lss piston either into the suction passage` of the engine o r into Athe cylinder on the other side 'of the piston, or both, and the brake. mechauisrn will be retracted together with the piston'of the actuator, by the retracting means for the brakes, as the spring, 73. When the Apressures on opposite'faces of the diaphragm,

8, and. disc valve, 10,'have been completely equalized, there will be a maximum differential of fluid pressures uponr the inner marginal portions, 15a, of the diaphragm, 15, between the seat, 7m, and the `valve actuating part, as previously stated, which'will hold the valves innormal position and provide the initial resistance to. be overcome by the operator.' A spring. indicated at 81, mav be provided to return the pedal. 80,and hold it in the off or released position where the 'Weight ofthe pedal exceeds the differential of fluid pressures lon the diaphragm, 15.

It will be notedythat whenever a differenti al of fluid'pressures exists on opposite faces of. either diaphragm valve', this differential of pressures acts in a direction to' seat the valve and hold it firmly seated to prevent leakage.` It will also'benoted that whenever ,pressures are fully equalized on the opposite faces of one diaphragm. the faces of the other diaphragm are subjected to the maximum differential of fluid pressures acting against the operator, and whenever a differential of fluid pressures exists simultaneously on opposite v faces of both diaphragme, the result or total differential of fluid pressures acts against the operator. The area of, the exi' 'po-sedfaces of the diaphragm, 15, norfmally exposedto the maximum differential of pressures Whenthe valve is in released position Jbeing much smaller than-the area of the diaphragm 8, on the opposite facesof which fluid pressures are equal in the released pol jected to anincreasing differential of fiuid.y

` sitionrit naturally follows that when pres sures are equalized on the diaphragm, '15, and the opposite faces ofdiaphragm, 8, are sub pressures over a larger area, a resistance or Areaction will be built up which will be felt .by the "operator and apprise him of the stantially the' same areas.

amount of power being applied tothe brake mechanisms by-theactuator. y

Our improved valve mechanism herein shown and described may beconstructed in such a manner that the reactionary feature may be omitted, if desired, by making the exposed areas of both diaphragme of sub-A Such 4`a construction is illustrated as a'modification in Fig. 4, 7 e

in which the parts corresponding with those shown in Figs. 2 and 3 are given the same reference'vnumbers with the addition of 100.` -As shown in this figure, the construction 0f .1065,l is provided interiorly with an annular wall, or seat', 116e. The diaphragm, 115, is`

in this instance provided with an aperture, or apertures, 123, communicating with-'the central chamber, 107, and ladapted to be .shut

vofl' from the atmosphere'in chamber, 116, by

a second valve, 125, carried by the valve actuating part, and held in seated relation withthe diaphragm,l 115,"when the parts are in the released position shown in Fig. 4.

As indicated'in this figure, when theparts are in the released positions, both faces of the diaphragm, 108, and disc valve, 110, will be exposed-to rareca-tion, and .the pressures thereon'will be equal. The inner face of the diaphragm, 115, will be exposed to rarefication in chamber, 107, as will' the inner face of thedisc valve, 125, the outer faces of said disc valve and diaphragm being ex-.`

posed to atmospheric pressure which'holds 'the parts in the released position and pro- `vides. the initial resistance which must be overcome by the foot of the operator.

In the operation of this form of valve I mechanism, `When'the valve actuatmg part,

120, is moved in the direction of the arrow in Fig. 4, to applythe brakes, the disc valve, 110, will be seated, cutting off the central chamber, 107, and the. cylinder in rear of the piston from the suction passage of the en gine, and thereafter the disc valve, 125, will be unseated'from the diaphragm, 115, to adl mit atmospheric air to the chamber, 107, and I.

to the portion f the cylinder inrear of the piston. This movement will beresisted by the initial resistance provided by the difier ential of fluid pressures on the diaphragm, 115, 'and disc valve, 125. When the valves have been movedfto the osition tol effect a power stroke, andatinosp eric air begin:I to

.a pressure i therein,

v taneously disc valve, 110, so that there will be no inl crease in the pressure exerted on the foot of the operator in opposition to the movement of the pedal lever, or in other words,

. the initial resistance will remain unchanged.

7 in Figs. 2 and 3,*in

i seat in lie'u of the f suitable material, to engage the valvevseat,

ing w1ll,as'soon 5 c. 224, the inner face of l through apertures 217.

lOtherwise the device operates in exactly the samema'nner as previously described and the differential o`f fluid' pressures on either diaphragm will always be ina direction to restore the parts to released position.

'1n Fig. 5 we have shown vvanother slight modification of the valve mechanism shown which we'employ a disc valve for directly engaging the annular valve diaphragm type of valve illustrated in those figures,fat 15. In Fig. 5

the parts corresponding with those shown in Figs. 1, 2 and 3 are given the same reference characters, with the addition of 200. The construction of the valve casing is identical with that previously described with-reference to Figs. 2 and needl not be further ref' ferred to.v The" valve actuating part, I220, is provided withl a rigid disc,-indica ted at indicated at 215, of

a sealing valve member,

or other compressed cork, cork-composition,

indicated at 2075, for closing off the com-I munication .between the central chamber, 207, Aand the exterior chamber, 216, which is inv communication with the atmosphere The operation of thisvalve mechanism will 4-5 be exactly the same as'thatA previously described with reference to"Figs.2 and 3, and

" need not be repeated.

In Figs. 1 to 5 we have illustratedthe valve mechanism arranged to be inserted in linkage i the United between the. operator operated part and certain brake mechanism of vthe vehicle, preferably the brake mechanism for the rear or non-steering wheels, to whichthe physical force of the operatorvm'ay be applied when desired, as previously explained. We wich4 it to be understood,however,. that this for' of valve mechanism may also be employed in linkage between the operator operate" part and a fixed part connected `with'the veh icle, yielding resistance means, as a spring. being inserted between the valve casing and the part to which it is connected,ras in our former application for "Letters .Patent' of States filed June 6th, 1928,and given Serial No. 283,182, and in such 'ari r 'valve casing,

, withl Aan arm,

the pedal to move' which is provided with 'When the tension of spring,

desired, for enabling the operator to addhis physical force to certain brake mechanisms if We havel illustrated such a constructionin Fig. 7, in which the parts corresponding to those shown in Fig.` 1 are given the-same reference numerals with the additionlof300 to avoid repetition. In this construction the chassis by a yoke, 330, provided with a stop, 331. The valve `casing is connected by a spring, 350, with a part connected with the 306,is-v suspended from the c chassis, in this instance a fixed part, and the valve actuating part, 320, is connected by link, 382, with pedallever, 380. A power applying lever, 390,\is connected by link rod,

'379,' with brake mechanism, in Athis instance being connected to an arm, 377 a, on the rock shaft, 37 61, and the lever, 390, is provided pedal lever and having a pro]eetion, 392, in

' the path of said pedal lever.

The forward movement of the pedal will.

ward and increase the tension of'spring, 350, until it presents sufficient resistanceto enable the valveJ actuatingpart with respect to the valve casing and operate the valves vto effect the application of the brakes. If the operator stops the forward movement of the pedal, thev differential of fluid pressures onthe opposite faces of the.

391, extending forward of the in this instance move the valve casing for- Ice diaphragm and disc valve and onthe opposite faces of the lrear wall ofthe valve casas it is suicient to overcome the spring, forward and vseat the diaphragm, viding the follow-up operationofthe valve.`

350, is increased beyond a point where it can be overcome by the maximum differential of iuid pressures on the valve mechanism, the brakes will have` been applied'with the full force ofthe actuator, andthe operator by 'further depress-A 350, move the valve vcasing '.thus. pro-4 ,c

ing the pedal lever can bring it intovcontact,

with theprojection, 392, and-apply his`physi' cal force in addition to that of the operator.

The operator can also apply the brakes by lphysical force alone, through projection, 392,' and the parts connected thereto..

` Where we have referred to the portions of the cylinder forward of the piston and rear of the piston, these terms are to'be und -derstood with reference to the stroke'of the` piston and not with referenceI to the vposition -of the cylinder with respect to the vehicle, that is to say,

the portion of the cylinder for Ward of the piston is located on the side there'- of toward which the power stroke is made, and rear of'the piston vrefers to the portion of the cylinder on the opposite face of the piston regardless'of the manner in which the piston isiarranged with respect to the vehicle. 'A

Vhat- We claim and vdesire ters Patent vis l. vIn vvalve mechanism for controlling power actuators, the' combination with a valve casing provided with adjacent chamberspr'oto secure by Letvided with an aperture for7 placing them in communication, valve means for controlling said communicating aperture havmg oppositely disposed faces subjected at all times to the pressures in said respective chambers, means for connecting one of said chambers yat all times with a source of lower fluid pressure, means for connecting said lower pressure chamberat all'times with a portion of an actuator on oneside of a movable member thereof, means for connectingthe other of said chambers withthe actuator-on the other side of said movable member, said last mentioned chamber having an aperture for admitting higher pressure fluid to said second chamber, a second valve means for closing said aperture having its outer face cxposed at all times to thehigher fluid pressure and normally holding said second valve means in closedv position, valveA actuating means connecting said second means with said first' mentioned valve'means and holding the latter in position to connect said chambers when said former valve memberis heldin closedposition bythe higher pres-I sure fluid to connect vthe actuator on both -casing,a diaphragm valve having portions in sealing engagementtherewith and forminga chamber ontheouter s1de ofsaid d1aphragm, means for connecting said chamber at all times with a source-oflower fluid pressure andvwith portions'of an actuator-on one side of a movable member thereof, .a disc valve in said chamber having a diaphragm engaging seat, said casing being provided with a second chamber on the opposite side of said diaphragm, means for conneching said secondchamber with nportions of the actuator on the opposite side of said movable member thereof, saidv second chamber being provided withv an aperture for the ad- 'mission of higher fluid pressure thereto, valve means for closing said aperture having its .outer face exposed at` all times to the higher fluid pressure, and its inner face to the fluid pressure in said second chamber, said diaphragm being provided with an Aaperture for connecting said chambers vlocated in position to be' closed when said disc valve is seated thereon, a valve actuating'part coni part. A

necting said valve meaiis with said; diay phragm and disc Valve, and sealingly engag ing thesame and holding said disc valve unseated' when said valve means is held in closed positionby said higherl fluid pressureon its 'outerlfaceg to connect the actuator on both sides of its movable portion with the source of lower fluid pressure, whereby ywhenever either said valve means or the diaphragm and disc valve are in closed position, a differential of fluid pressures will exist on the opposite faces thereof tending to hold it firmly' closed, and an operator operated part connected with said valve actuating part.

' 3. In valvev mechanism, forcontrolling power actuators, the combination with avalve' casing provided with`adj acent chambers provided with an aperture for placing them in communication, valve meansfor controlling said communicating aperture having oppositely disposed faces subjected at all timesto lthe pressures in saidv respective chambers,

means 4for connecting one ofsaid chambers at all times with a source of lower fluid pressure, means for connecting said lower pressure chamberat all times with a portion of an actuator ou one side ofa movable member thereof, means for connecting the other of. said chambers with the actuator onothe other side ofv said movable member, said lastmentioned chamber having an 'aperture for admitting higher-pressure fluid to said second chamber, a-second valve means for closing, said aperture having its outer face exposed at all timesto the higher fluid pressure and normallyV holding said second valve means in closed position, valve actuating means connecting said second valve means 'with said yfirst mentioned valve means and holding the latter in position to connect said chambers '.whe'n.. said former valvemember is held in closed position by the higher pressure. fluid,

to connect the actuator on both sides of its.

`said movable member with the source of lower pressure, and an operator operated palrt connected with"said valve `actuating part,the portion of said second 'valve means subjected on its opposite faces tol differen-V tial, fluid pressures when in vclosed position being of less area'thanthe'portions of said."

irst mentioned valve means exposed onoppoi site faces to differential fluid pressures when in closed position, and the differentials of pressures on both valve means acting to re-- sist `the movement of said operator operated part in' a direction to move said second valve means to .open position, and said first-l.valve means to closed positiomwhereby saidmovement will effect the building upv of an4 in# creased differential of fluid pressures on the larger areas of said first valve means which Will be transmitted to the el. In valve 4mechanism for 4 controlling power actuators, Vthe combination vwith a operator operated I a diaphragm valve having porvalve casing,

engagement therewith and tions in sealing forming a 'chamber on the outer side of said l"bergat all times with a source o said'chamlower Huid pressure and with portions of an actuator on one'side of a movable' member thereof, a disc valve in said chamber having a diahragm engaging seat, said casing being prodiaphrgam, means Jfor connectin vided with a second chamber on 'the opposite sidel of. said diaphragm,y means lfor connecting said second chamber with'porv tions of the actuator on the opposite side bt v said movable memberthe1eof,said second thereto, valve means .ture having its outerv face exposed at .all -tlmes to the higher fluid pressure, and its chamber being provided with an aperture.

@for the admission of higherl iuid pressure 'for closing said aperinner Aface to the `fluid pressure in said second chamber, said diaphragm being provided with an aperture bers-located in position to be closed when said diaphragm and gaging the same and holding said disc valve disc valveis seated thereon, a valve'actuatingl part connecting said valve means with sai disc valve, and sealingly en- I unseated when said valve means is held in both sidesv ofv Y and disc valve exposed on opposite faces vdifferential fluid pressures when in fseate relation, and the'di-tlerentials of pressures on both valve means acting to resist the move-v ment of said operator operated part in a direction to move said valve means to open position and to seat said disc valve, whereby said movement willeifect the building up of f an increased die'rential of. fluidpressures on the larger areasof'said diaphragm and disc A valve, which. will .be transmitted tothe .op-

valve casing, a diaphragm valve having portions ber at all times with a' source of lower erator operated part.

- 5. In lvalve mechanism for controlling phragm power actuators, the combination vwith a in sealing engagement therewith an forming a'',chamber on the outer side of s ald diaphragm, -I neans fluid pressure andwithportions of an Aactuator on one side of a movable memberthereof, a 'disc valve in said'v chamberv havingadi'aphra Second chamber with on the opposite side of said movable memberthereof, said second'chamber being pro` for connecting said cham? provided with a seat,

with said Y seat, exposed on its inner t0` fhigher pressure for connecting said chamsaid .operator operated part diaphragm valve 'and seat `the disc vvalve'will effect thebuildin i y.creased iiuid pressure on the rst diaphragm,v

engaging seat, said-casing being provi ed valve and the dis'cvalve, whichpwill be transwith a second chamber on the .opposite'side of said diaphragm, means for connecting said portions of the actuator' vided with. 3, seat, a second 'diaphragm 'for' 4 engaging said seat, exposed on its-inner face second chamber, and

'1o means for admitting higher f to said second chamber when' tothe pressure in said on its outer face' to the higher pressure iuid at all times in a 'direction to seat-said diaphragm valve, pressure fluidv said second diaphragm valve is unseated, a valveactuating part connected sealingly with said.v diaphragms, and said discl valve, the pressure ofthe higher pressure fluid on said second diaphragm valve normally'holding it lseated and the disc valve unseated, andan operator operated part connected with said valve actuating part.

6` In valve mechanism for controlling bination with a power actuators, .the co valve casing, a diaphragm valve having por' tions'in sealing engagement therewith and forming a chamber on diaphragm, means berat all times with a source pressure and with portions of an -actuator on one side of a movable member thereof, a disc ,valve in said chamber engaging seat, `said casing being provided the outer side of said-` or connecting said chamof lower uidwith a second chamber on'th'e opposite side I of -saidf diaphragm, said second chamber with actuator on member thereof, said second chamber being .a secon diaphragm portions of the or engaging said facev to the pressurein saidsecond chamber,

"fand on its outer face to the higher pressure -iiuid at all times in a direction to seat said diaphragm valve, means iuid to said when said second diaphragm seated, a 4valve actuatingipart connecte sealingly with said diaphragmsvandsaid disc valve, the vpressure of the higher pressure Huid on said second diaphragm valve normally holding it seatedand the'di'sc valve unseated, and an operator operatedpart con'- said valve actuating partjthe' portion of saidv secondndiaphragm exposed" faces. to differential Huid prestor'operated part,

lto unseat said second kup of an 1nmitted .to the operator operated part.

means for' connecting the opposite side of said movable for admitting second chamber i valve isunl dit'erentialof pressures on both of said valve -means resisting the movement 7. In valve'. mechanism --for' controlling power actuators, the valve casing, a diaphragm valve having portions in sealing engagement therewith, and

combination with 'a having a diaphragm 90 Y .forming a chamber on the outer side of said diaphragm, means for connectin said chamber at all times with a source o lower fluid pressure and with portions of an actuator on one side of a movable member thereof, a disc valve in said chamber having a dia- I t phragm engaging seat, a second diaphragm valve inl said caslng, having portions in seal-l ingv engagement therewith and forming a central chamber between said diaphragms,V aK

' y 25 ly engaging the same, said second diaphra being ncrmallyheld in seated posltion y the .higher vpressure fluid and holding said .disc valve unseatedto connect the actuator on both'sides of said movable member thereof with the source of lower pressure.

rengaging said' second diaphra l tioned diaphragm .being provided with an 8. In valve mechanism -for controllingy power actuators, the combination with a valve casing, a diaphragm valve having portions in sealing engagement therewith and 4forming a chamber on the outerside of said diaphragm, means for connectin said chamber at all times with a source o lower fluid pressure and with portions of an actuator on one side of a movable member thereof, a disc 0 valve in said-chamber having a diaphragm' engaging seat, a second diaphragm valve in "said casing having portions in sealing en gagement therewith and forming a central chamber between said diaphra-gms, a seat for means for connectingsaid central .cham r with portions of the actuator on the opposite side of v said movable member thereof, said first menaperture for connecting said chambers located in position tobe closed when said disc valveis seatedf,said second diaphragmv having an aperture therethrough for admitting higher pressure fluid to said central chamber" located in position to be closed Vwhensaid second ydiaphragm is seated, anda valve acj tuating part connected with said diaphragms v.and disc valve and s ealingly engaging the same. said second diaphragm being normally '60 held in seated position by the higher pressure fluid and holding said disc valve unseated,

the connections between said diaphragms- 'and disc valve and the valve actuating part either direction, whereby whenever either of said diaphragme are seated, a diierential of fluid ressures will be created on opposite sides t ereof, tending to hold it rmly seat ed and prevent leakage. f

9.` In valve mechanism for controlling power actuators, the combination with a valve casing comprising a central member provided with a central chamber open at both ends, an end member provided with a lower pressure chamber and with means for connecting said chamber with a source of Huid pressure and witha portion of the actuator on one side of a movable member thereof,'a secondfend member provided with a higher sov pressure chamber and means forconnecting l it with a source of higher fluid pressure, two

diaphragm valves each having marginal portions clampedbetween said central member and one of said end members, means for unlting sald casing members, a disc valve 1n said lower pressure chamber provided with a seat for engaging the adjacent diaphragm valve,- said diaphragm valve being provided with apertures for establishing communication between the lower pressure chamber and `the 4central chamber and located in position to be closed when the disc valve and said diaphra m valve are in seated relation, the other o lsaid diaphragm valves being provided with a seat and with apertures for connecting the higher lpressure chamber with said central chamber and located .in position to be closed when said diaphragm is seated, said central chamber being provided with means for connecting it with the portion of the actuator on the opposite side of v said movable member thereof, a valve actuating partconnectingv said diaphragm valves and said disc valve and sealingly engaging the' same and having a portion extending outside of said casing and holdin said valves in position to unseat rone of sai diaphragm valves 'after the other is seated by a movement'in eitherdirection, the higher iiuid pressure holding said second diaphragm seated and the rst diaphragm and disc valve in unseated relation, to connect the actuator on both sides' of -said movable member with the lower fluid pressure source.

10. In valve mechanism for controlling power actuators, the combination with a valve casing comprising -a central member provided with a central chamber open at both ends, an end member provided with a lower pressure chamber and with means .for con,.

ne'cting said-chamber with a source of fluid pressureand with a portion vof the actuator on one side of a movable member thereof, f

a second end member rovided with a higher pressure chamber an means for connecting it lwith a source of higher'tluid pressure, two diaphragm valves each having marginal poro being constructed to unseat one diaphragm -tions clamped between said centrah member ual after the other is -seated by a movement in and one of said n'd members, means for unit- 1e phragm valve are in seated relation, the other of said diaphragm valves being provided with a seat and with apertures for connecting the higher pressure chamber'with said central chamber and located iii position to be 'closed when said diaphragm'is seated, said central chamber being provided with means for connecting-it with the portion of the acf tuator on the opposite side'of said movable member thereof, a valve -actuating part connecting said diaphragm valves and said disc valve and sealingly vengaging the same :and

'having a :portion extending outside offsaid casing and holding said valves 1n position to unseat oneof said diaphragm'valves after the other is seated by a movement in either direction, the higher fluid pressure holding said secondv diaphragm seatedand the tirst diaphragm and disc valve in unseated relation, the portion of said vsecond diaphragm Within said seat being of less area than the opposite faces of the first mentioned diaphragm and disc valve exposed to differential pressures when. in seated relation.

11.' In1 a brake system for automotive vehicles provided with an internal combustion engine for propelling the same having a throttle controlled suction passage, the com-` bination with a power actuator,'comprising a cylinder closed ,at both ends, and a piston in said cylinder, and brake mechanisms operativel connected with said actuator, 0f-a control -ing valve for said actuator comprising a valve casing having adjacent chambers,

and providedwith an aperture for placing them in communication with'each other, valve means for closing' saidaperture havingopposite -faces exposedre'spectively to the pressures in said chambers, a tubular connection from one f said l,chambersjto said suction ",piston, means for connecting the said second passage, a tubular connection from `said chamber to the portion of said actuator cylinder forward of the piston, a tubular connection from )the other of said chambers to the portion `of said'cylinder in rear ofi the.

chamber' with a source'of higher fluid Apressure, a second valve means having opposite faces,- the 'one exposed to the higher fluid pressure acting in a direction to close said' connecting means, and the other eXpised to lthe pressure in said secondchainber, la valve 4actuating part connecting .said valve means,A and constructed to eEect the'movementcf one to open positionafter the other is movedJ to closedposition'by a movementin either direction, the differential yof fluid pressures apply his physical force to 4on said vsecond valve means holding it in closed position, and the first valve means in open position, When 1n released position, to

`maintain both of said chambers in communication with'said suction passage and the actuator piston submerged in vacuum, and an operator operated part for effecting relative movement betweenthe valve actuating part and the valve casing.

12; In a brake syst-em for automotive vchicles .provided with an internal combustion engine for propelling the sameA having a throttle controlled suction passage, the combination with apower actuator, comprising a-cylinder closed at both ends, and a piston in said cylinder, and brake mechanisms operatively connected with said actuator, of a` controlling valve for said actuator comprising a valve casing having adjacent chambers, 4 and provided With an aperture for placing i them in communication with each other, valve means for'closing said aperture having opposite faces exposed respectively to the pressures in said chambers, atubular connection from one of said chambers to said suction passage, a tubular connection from said chamber to the portion of said actuator cylinder forward of the piston, a tubular connection from the other of said chambers to the portionof said cylinder in rear of tlie piston, means forl connecting the said second chamber with'a source of Vhigher fluid pressure, a second valve means having opposite faces, the one exposed to the higher fluid pressure acting in a direction to close said connecting means, and the other exposed to the pressure in said second chamber, a valve actuating part connecting said valve means, and constructed to eii'ect the movement of one to open position after the other is moved to 'closed position by a movement in either direction,fthe' diierentialof fluid pressures on said second valve means holding it inl closed position, and the first valve means in open position, when' in released position, to maintainboth of said chambers in communication with, said suction passage and vthe actuator 'piston' submerged in vacuum, and an operici;

ator operated part for eecting relative movement between thev valve actuating part and the valve casing, and connected with certain of -said brake mechanisms, by means providing lost motion to'permit the operator to the brake mechanisms connected therewith. f

' 13. In 'a brake system for automotive ,ver hicles provided with'an internal combustion engine for propelling the', same having j a throttle controlle'dsuction passage', the com'-, bination with apower actuator, comprising a cylinder closed at -both ends, and a' piston in said cylinder, and brake 'mechanisms operatively' connected with said actuator, ofja' lib' controlling valve` for said actuator comprising a valve casing, a diaphragm' valve havsaid diaphragm valve pressure in va directi ing portions in sealing engagement therewith and forming a chamber on one side .of said diaphragm, a tubular connection from said chamber to said suction passage,V a tubular connectionfrom said chamber to the portion of said cylinder forward of the piston, a disc valve in saidchambenhavinga seat for engaging the diaphragm valve, said casing being provided with a seco-ndchamber separated from the first chamber by said diaphragm valve, a tubular connection from said second chamber to the cylinder in rear of the piston, being provided with an aperture for connecting said' chambers` located in position to be closed when said disc valve is seated,'said second chamber being provided with an aperture for connecting it with a'source of higher Huid pressure, valve means for closing said `aperture having one face exposed atall times to the higher fluid on-to effect the closing of said aperture, and the other face exposed to the pressure within said second chamber,`

avalve actuating device connecting said valve means with-said diaphragm' valve and d isc valve, for holding the disc valve unseated when the said valve means is 'seated by the diiierential of iiuidpressures thereon, to connect-the actuator cylinder on both sides of the piston with-said suction passage, and an operator operated part for effecting relative movement between said valve'actuating part and the casing, for opening said valve means after` seating said disc valve, t'o effect the power stroke of the actuator pist-on to apply the brake mechanism.

14. In a brake system for automotive vei, hides-provided with an internal combustion bination with a power actuator,

engine for propelling thev same having `a throttle controlled suction passage, the coma cylinder closed at both ends, and a piston in said cylinder, and brake mechanisms operatively connected with said actuator, of a controlling valve for said actuator comprising a valve casing` 'a diaphragm valve hav-v ing portions in sealing engagement therewith and forming a chamber on' one side of said diaphragm, .a tubularl connection from'said chamber. to said suction passage, a tubular connection-from said chamber to the portion of said cylinder forward of the piston, a disc vvalve in said chamber, having aseat for en- 1 gaging the rdlaphragm valve, said' casing being provided with a second chamber separated'fromtheI iirst chamber by said dia- 3 phragm valve, a tubular connection from said second chamber'to the cylinder in rear of the piston, said diaphragm valve being provided with an aperture for connecting said chambers, located in position to be closed when ,said disc valve is seated,` said second 'chamber being provided with an aperture vfor connecting it with a source of higher-fluid pressure, a diaphragm valve, and a valve seat surcomprising rounding said aperture, a-second diaphragm for engaging said seat having marginalportions in sealing engagement'with the casing and provided with an aperture for admitting higher pressure fluid to the said suction chamber, when said second diaphragm valve is unseated, a valve actuating part connecting said diaphragms and disc valve and constructed to unseat the disc `valve when the second diaphragm valve is seated, and an operator'operated part forA effecting a relative movement between the valve casing and the valve actuating part.

15. In a brake system for automotive vehicles provided withan internal combustion.

engine for propellingy the same" having a throttle controlled suction` passage, the comnection .from one of said chambers to said suction passage, a tubular connection from Said chamber to the portion of said actuator 4cylinder forward of the piston, a tubular connection from the otherof said chambers .to the portion of said cylinder in rear of the piston, means'for connecting the said second chamberwith a source of higher fluid pres-- sure, a second valve means having-opposite faces, the one exposed to the lgher -fluid Y pressure acting in a direction to close said connecting means", and the other exposed tol the pressure in saidl second chamber, a valve actuating part connecting said valve means, and constructed to leffect the movement of one to open position after thejothe is moved vto closed position by a movement in either direction, the differential of fluid'pressures on said second valve means holding it .in closed positiontand the first valvemeans 1n' open position, whenin released position, to maintain both of said chambers inj communication with said suction passage and the actuator piston submerged invacuum, and an v operator operated part, said valve casing and the valve actuating part being connected vthe one with said operator operated part and the other with Drake mechanism for thevvehicle, 'and means for limiting the 'relativemovement between the valve actuating part and said casing, to enable the operator to apply his physicalforce to said brake mechamsm. v i- 16.v In a brake system for'automotive vvehicles provided with an internal combustionengine for ,propelling the same-having a throttle controlled suction passage, the com- .eratively connected with said actuator, of a controlling valve for said actuator compris- 'ing a valve casing,-a diaphragm valve having portions in sealing engagement therewith and forming a-chamberon one sideof of' the piston,

' chamber being provided 'between the valve actuating partandfsai I hicles provided 5 controlling valve' be1 s,-andI provided withr said chambers,

lto the higher fluid v i means is seated by the "35 said diaphragm, atubular connection from said chamber to said suction passage, a tubu- Y.

lar' connection from saidchamber to the portion of said cylinder forward of the'piston, a disc valve in said chamber, having a seat for engaging the diaphragm valve, said casing being provided with a second chamber separated from the rst 'chamber by said diaphragm valve, a tubular connection fromsaid second chamber vto the cylinder in rear said diaphragm valve being provided with an aperture for connecting located in position to be closedwhenA sai-d disc valve-is seated, said second with an aperture for connecting it with a 'source of higher fluid pressure, valve means for closing said aperture having one face exposed at all times pressure in a direction to edect the closing of said aperture, and the other face exposed to the pressure within said second chamber, aivalve actuating device connecting said valve means with said diaphragm valve and disc valve, for holding the disc'-valve unseated when,the said valve dierential of fluid pressures thereon, .to connect the actuator cylinder on both,l sides .y of the piston with, said suction passage, and an operator operated part, said valve actuating .part'land the valve casing being connected the one with said operator operated part and the other with brake mechanismfor the vehicle, and means Vfor limiting t je' relative` movement casing, to enable the operato1'to-apply his physical force to said brake-mechanism.

`17. In a brake system for automotivefyv with an internal combusti engine -forpropellingn thesame having hrottle controlled suction passage, theco'm-fl opposite faces `comprisingination with a power actuator, a cylinder closed at both ends,'-`a'nd a lpiston inf said vcylinder, l eratively connected 'with said actuator, of` a y forA said actuator com ing a valve casing havingadjacent lcha Y an. aperture@for placing them in "communication, with; `each othenyalve-meansfor closing lsaid' lapert111je1 having,".oppositefaces v"exposed, respectively to thefpressures in saidl chambers,a tubul lconnection from one-of saidl chambers to' said suction passage, .y ,a tubular connectionfromj said chamber to thefp'ortion of. said actuator; cylinder forward .'ofthe piston, a tubular; connection from the other of `said 'chambers and brake 'mechanismsiop-f;

to the portion the piston, means forconnecting the said second chamber with a source of higher fluid pressure, a second valve means havingop'posite faces, the one exposed to the higher Huid 'pressure acting in. adirection toclose said connecting means, and the other exposed to the pressure actuatingpart connecting said valve means, and constructed to effect the movement of one to open position after the other is moved to closed position by a movement in either direction, the differential of fluid pressures on said second valve mea-ns holding it in closed position, and the first valve means in open position,when in released position, to'

maintain both of said chambers in cemmumcation with said suction passage and the actuator piston sub-merged in vacuum, portion of said secondvalve means. having its opposite -faces exposed to differential pressures when seated being of considerably less area tioned valve mechanism exposed on opposite faces to differential pressures when in seate position, and an operator operated part for effecting relative movement between the valve actuating part and the valve casing, to enect the power stroke of the actuator and build up a pressure corresponding to'that in the cylinder in rear of the piston,

being transmitted to the operator through the operator operated part. v Y v 18.' 1n a brake system for automotivevehicles provided with an internal combustion engine for propelling thek same throttle controlled suction passage, thecombination with a power actuator,'comprising a cylinder closed at both ends, and a piston in said cylinder,

controlling valve for said actuator comprising a valve casing having adjacent chambers, and provided .with an aperture for placmg them in communicationfwitlrech other, cvs ilve means for closing saidv aperture having exposed respectively Y, to the chambersfa' tubular connec- `pressures saidl said chambers :to sald suction from'one of chamber to the portion of lsaid actuator cylinder forward of the piston, a tubular @ouncetion from the other of said chambers portion of saidfcylmder than the portions of said first menbetween said valve means the diii'erential of fluid pressures on said valve neans effectedv therebyhaving a and brake mechanisms opd ,eratively connected with said actuator, of a to the` in af of the pistes of said cylinder in rear of in -said secondchamber, a valve the tion passage, a vtubular connection frorrrsaidv Y means for'connecting thegsaid second chamber .with a source fofhigher'jfluid pressure, a 1"" "second valve vmeans havingopposite faces,

' the oneexposed tothe'lhigher Huid pressure acting in a direction.y toiclose said connecting means, and the other-'exposed to the pressure in said-. 'jsecond :chamber aqvalve actuating part conectingsaid-valve means, and constructed'toelect themovement of one to open position after the other is moved. to closed- Y position by a movement in either direction,

l l said chambers in communication withI said' the diierential or iuid pressures on said second valve meansA holding it in closed position,

and the lirst valve' means in open position, when in released position, to maintain both of suctionpassage the actuator piston submerged in vacuum, the portion of said second valve means having its opposite acesexposned said vvalve4 actuating part being connected the oneto the operator operated part and the other to brake mechanism of the vehicle, to

enable the operatorv toapply his 'physical force to said brake mechanism.

19. In a lbrake system for autbmotive vehicles provided with an internal combustion engine vfor propelling the same, having 'a throttle controlled suction passage, the com bination with a power 'actuator comprising a v cylinder closed at both ends, and a piston in 'said cylinder, and 4brake mechanism operatively connected withsaidv actuator, of acontrolling valve for sald actuator comprising A`a valve casing, al diaphragm valve having portions in sealing engagement therewith and forming a chamber on the outer side of said diaphragm, means for connecting said chamber at all times with the suction passage of the engine and with the actuator cylinder forward of the piston therein, a disc valve in said chamber having a diaphragm engaging seat,f a second diaphragm valve in said casing having portions in sealing engagement A therewith and forminga central chamber be- -tween said diaphragm, a seat for engaging vsaid second diaphragm, means for connecting l 'said -central chamber with the cylinder in rear of they piston, said irst mentioned'dia-- phra'gm Vbeing provided with an aperture .for connecting said chamber located in position .to bef closed when-'said disc valve is seated,

said second diaphragm having an aperture therethrough ftrfadmittingv higher pressure -1 Huid-to said central chamber-located in posi- L A tion to be closed when said second diaphragm is seated, portions of said second diaphragm exposed toditerential pressures on opposite faces when seated being of materially less area than the portions of said first mentioned diaphragm, and the discvalvevexposed to i differential pressures when the disc valve is seated,l the valve actuating part connecting said second diaphragm with' said first men- -tioned diaphragm and'disc valve, the difierential of fluid pressures on 'the second diaphragm holding the disc valvevunseated when the parts are'in released position, and

an operator operated part', said valve casing and said valve actuating part being connected, the onev with said operator operated part,

and the other with brake mechanism for the vehicle, and means for limiting the relative movement of the lvalve actuating part with respect to said casing.

20. In a brake system for automotive vehicles provided .with an internal combustion engine for propelling the same having a Y throttle lcontrolled suction passage, the combination with apower actuator, comprising a eylinderclosed-'at both ends, and a piston in said cylinder, and brake mechanisms operatively connected with said actuator, of a controlling valve for said actuator comprising a valve casing having adjacent chambers, and provided with an aperture for placing them in communication --with each other, valve means for closmg-sald aperture having opposite faces exposed respectivel to the pressures in said chambers, a tub ar connection from' one of said chambers tol said suction passage,.a tubular connection from said chamber-to the portion of said actuatoncylinder forward of the piston, a tubular connection Vi'rom the other of said chambers to the p0r-` tion of saidv cylinder in rear of the piston,

means for connecting the said second chamber with a source o'f higher duid pressure, a second valve means having opposite faces, the one exposed to the higher fluid pressure acting in a direction to close saidV connecting means, and the'other exposed to the pressure in said second chamber, a valveoactuating part connecting said valve means, and constructed to effect the movement of one to open position after the other is moved to closed position by a movement in either direction, the diiierential of fluid pressures on said second valve means holding it in closed position, and the rst valve means in open position, when in released position, to maintain both of said chambers in communication with said suction' passage and the actuator piston submerged in vacuum, and an operator operated part, said valve actuating part and said valve 'casing being the one connected with said operator operatedpart, and 'the other connected with certain of said valve mechamsm, operatively :connected with the actuator less than'the whole numberthereof, and means for limiting relative movement of the valve actuating part with respect to the valve casing, whereby said operator operated part may be operated to apply all of said brake mechanisms by power, and to apply the physical force of the operator to said certain brake mechanisms with 'which it isconnected.

21. In a brake system'for automotive vehicles provided with an internal combustion engine for propelling the same having a throttle controlled suction passage, the combination with a power actuator, comprising a cylinl 'lso

inder closed at both ends, and a piston in y 'e i -11,826,450

S tively connected with said actuator, of a. con. trolling valve for said actuator comprising l a valve casinglhav'ing adjacent chambers, and v y provided wit an "aperture for-placing them- Y '5' in communication with each I other, valve means for closing said aperture havingoppo- Vsite faces eX osed respectively tothe pressures inv sai chambers, a. `tubular connection from one of said chambers Ato said suc-- 10 tion passage, a tubular connection from said chamber' to the' portion of said actuator. cyliuder forward fof the piston, a tubular connection from'the other of said chambers to'thef portion of said cylinder in rear of the piston, V1&5 means for connecting the said second cham-- f ,doer with a source of higherriudpressure, 'a 4second valve'means having opposite faces,

the one exposed to the higher fluid pressure y acting in a direction to close said connecting '20 means', and the'other exposed-to the pressure in said second chamber, a valve actuatlng part connecting saidv valve means, and constructed to effect the movement'of one to o en position after the otherlis moved to close position by v 25 a movement in either direction, the difieren- K tial of fluidv pressures von said second valve' means holding it in closed position, and the A rst valve means in open position', when in released position, to maintain both of said 130 chambers in communication with said suction passage'and the-actuator 'piston submerged 1n vacuum, theportionlof said second valve Y :means the opposite facesv of\whichv are-ex- .posedl to differential pressures in the closed 35 .position thereof being of less Iarea than the:l

opposite faces of said irst mentioned-valve means 'exposed to differential pressures -when x `inclosed positioman operator operated part, w said valve casingandivalve actuating `l'neans 40 beingthe one connected tos'aid operatoro'p erated: part, andjtheother connected to ce1' tain of 'said vbrake mechanisms less than the Whole number with which the vehicle isV provided, means for limiting the relative "45 movement betweenthevalve actuating. part,

andthe valve casing, whereby all ofsaidbrake. mechanisms may be applied by. power andthe. operator may apply'hi's physical force to, certain of said brake mechanisms 'connected -50.thereWith.' f f c, Y In testimony whereofv wedaiix our signaf, 

